Brush filament and construction therefor

ABSTRACT

A BRUSH FILAMENT OF POLYMERIC MATERIAL OF NOVEL COMPOSITION AND STRUCTURE PARTICULARLY ADAPTED FOR USE ON NONUNIFORM INTERRUPTED SURFACES SUCH AS VEHICLE SURFACES. A BRUSH FILAMENT OF LIGHT WEIGHT, LOW BREAKING STRENGTH, STRUCTURAL RIGIDLY SUFFICIET TO PROVIDE FULL CYLINDRICAL BRUSH CONFIGURATION AT RELATIVELY LOW RATIONAL SPEEDS, RESISTANCE TO WEAR AND FRAYING OR SPLITTING, AND FREEDOM FROM CURL AND MAINTENANCE OF SEPARATE DISCRETE FILAMENT RELATIONSHIP, THE FILAMENT INCLUDING A TUBULAR PORTION WITH SPACED LONGITUDINAL RIBS, THE RIB EDGES DEFINING PLANES TANGENT TO THE CONVEX SURFACES OF THE TUBULAR PORTION LYING BETWEEN SAID RIB EDGES.

p 20, 1971 "M. E. LONG 3,605,162

BRUSH FILMIENT AND cousmucrxon THEREFOR Filed March 14, 1969 IN vE/vraA?M/Jcs E. Iowa 9 W/M,fl ,/Z. {rm-a United States Patent 1 3,605,162Patented Sept. 20, 1971 3,605,162 BRUSH FILAMENT AND CONSTRUCTIONTHEREFOR Mace E. Long, Long Beach, Calif., assignor to Industrial BrushCompany, Pomona, Calif. Filed Mar. 14, 1969, Ser. No. 807,314 Int. Cl.A4611 1/00; D01d 5/00; D01f 1/00 U.S. Cl. -159 16 Claims ABSTRACT OF THEDISCLOSURE A brush filament of polymeric material of novel compositionand structure particularly adapted for use on nonuniform interruptedsurfaces such as vehicle surfaces. A brush filament of light weight, lowbreaking strength, structural rigidity sufiicient to provide fullcylindrical brush configuration at relatively low rational speeds,resistance to wear and fraying or splitting, and freedom from curl andmaintenance of separate discrete filament relationship, the filamentincluding a tubular portion with spaced longitudinal ribs, the rib edgesdefining planes tangent to the convex surfaces of the tubular portionlying between said rib edges.

BACKGROUND OF INVENTION Various types of brush filaments have beenproposed heretofore for use in brushing surfaces to be cleaned, as forexample vehicles such as automobiles, buses, rail cars, and nonuniformoften ornamental surfaces. Exemplary reference is made to automobilewashing apparatus known as car washes, in which an automobile is movedby a conveyor through a series of stations where various washing andcleaning operations are performed. At one of these stations cylindricalor configured brushes may be mounted for rotation about axes generallyparallel to the surface to be washed. Such brushes are rotatable atselected speeds so that free ends of the brush filaments thereon contactand strike the surface under pressure.

Prior proposed brush filaments for use in such car washes have been madeof oriented and nonoriented polymeric materials, each of such materialshaving certain desirable as well as undesirable characteristics for suchuse. Improvement of recovery characteristics after deformation has beenattempted with unoriented polyolefin filaments of cross-sectional shapessuch as described in U.S. Pat. 3,121,040. Strength characteristicsincluding stiffness, resiliency, and durability with a minimum mass ofmaterial have been sought by oriented filaments as described in U.S.Pat. 2,637,893. Filaments of relatively high stiffness, resiliency andstrength provided by an oriented polymeric material have requiredrelatively high rotational speeds of a brush means carrying suchfilaments because of the relatively heavy weight and size of suchfilament. Such oriented filaments have also exhibited a tendency tosplit, to fray and to part along lines of lamination produced byorientation of the material. Such splitting and fraying encourages andproduces entanglement of the split portions of a filament and also withadjacent filaments. Entangled and snarled filaments in such a rotatingbrush results in snagging and catching of door handles, sideviewmirrors, license plates and other projections or ornamentation on avehicle and results in damage. Often a sideview mirror may be pulledfrom the car.

Prior proposed filaments have also included a crosssectionalconfiguration which appeared to favor entanglement of split filamentportions, such as X, Y and various other cross-sectional configurationshaving a substantial amount of the material of the cross-sectionextending outwardly from the axis of the filament. Such configurationsice provided relatively deep longitudinal recesses or channels whichappeared to contribute to entanglement of the filaments.

Prior proposed filaments used in vehicle washing brushes were generallymade of a paraffin base material, such as certain polyethylenes, whichupon striking a surface often deposited a waxy-like streak on thesurface. Obviously such streaking of glass and metal surfaces on a carwere not desirable in a car washing and cleaning operation. Suchpolyethylene base material had a modulus of fiexure of about .06. 08 10p.s.i.

The present invention, therefore, contemplates a novel brush filament ofchemical and physical characteristics which obviate the disadvantages ofprior proposed brush filaments and which provide a low cost readilymanufactured brush filament having advantages and characteristics notpresent in prior proposed filaments.

The present invention contemplates a brush filament structure of tubularform having a relatively thin wall section and having a plurality ofspaced parallel longitudinal ribs extending from the external surface ofthe tubular portion a relatively short distance whereby the tubularportion is provided structural rigidity and an external configurationwhich does not show a tendency towards entanglement of individualfilaments in a brush means. The present brush filament is also made of apolymeric material of a virtually nonwaxy base to avoid streaking andwhich is only partially oriented so that splitting or fraying of thefilament is virtually eliminated.

The primary object of the present invention, therefore, is to provide anovel brush filament.

An object of the invention is to disclose and provide a brush filamenthaving a cross-section which enhances water holding and transfercapacity of the filament and provides sufficient rigidity so that fullcylindrical brush configuration will be achieved at relatively lowrotational speeds.

An object of the invention is to disclose and provide a brush filamentof novel composition which eliminates the deposit of wax-like streaks onsurfaces being brushed thereby.

Another object of the invention is to disclose and provide a brushfilament wherein the material is only partially oriented to an amountinsufficient to produce a laminar construction, thereby virtuallyeliminating fraying of filament ends and resulting entanglement whilethe filament structure provides rigidity, stiffness, and recovery fromdeformation to provide a filament especially useful in vehicle washing.

A further object of the invention is to disclose and provide a brushfilament of novel composition and structure wherein the rfilaments donot cling to each other but maintain separate discrete identity and donot become interlocked and entangled during a brushing operation.

A still further object of the invention is to disclose and provide abrush filament having a tensile strength in the order of 3 to 5 lbs. sothat said filament will break without damage to automobile ornaments andaccessories on the surface of a car.

A still further object of the invention is to disclose and provide afilament composed of a novel composition material which is onlypartially oriented and which has a low breaking strength and provides aclean, nonstringy fracture.

Other objects and advantages of the present invention will be readilyapparent from the following description in which the drawings illustratean exemplary embodiment of the invention.

'In the drawings:

FIG. 1 is an end view of a filament embodying the construction andcomposition of this invention.

FIG. 2 is a schematic view of the principal apparatus and method formaking the filament shown in FIG. 1.

FIG. 3 is a schematic fragmentary view of a brush means provided withthe filament of this invention.

FIG. 1 shows a brush filament generally indicated at 10 embodying thepresent invention. The exemplary brush filament 10 comprises anelongated tubular portion 111 having a generally cylindrical externalsurface 12. The wall thickness of tubular portion 11 is relatively thinand a typical wall may be in the order of .004 thick. A typical innerdiameter of the tubular portion may be in the order of .036". Filament10 may be cut to any selected length, as for example from 3 /2 and up.It will be understood that the dimensions indicated above are typical ofa specific example and may be varied. It will thus be apparent that anexemplary brush filament 10 is relatively small in materialcross-sectional area and dimension in relation to its length. Theinvention thereby comprises the provision of a novel polymeric materialcompounded, formulated, processed and extruded into a structural shapeso that an effective brush filament is provided with such dimensionalrelationships.

In diametrically opposite relation a plurality of parallel longitudinalribs 14 may project from external surface 12, said ribs having agenerally triangular cross-sectional configuration with a base atsurface 12 and terminating at longitudinal rib edges 15 of transverselyrounded configuration. The height of said ribs is related to thecurvature of the tubular portion lying between adjacent ribs 14. In theexample, a generally cylindrical tubular portion is illustrated, ribs 14are spaced about 90 apart, and adjacent edges 15 define a planeindicated at T which is approximately tangential to the external curvedsurface 12 of the curved wall section 16. Generally speaking, it may benoted that the square figure defined by rib edges 15 and planes Tconnecting said edges has inscribed therewithin outer cylindricalexternal surface 12 of tubular portion 11. Such relationship betweenedges 15, the curved wall therebetween and the plane T tangentialthereto may be provided with tubular portions inscribed within generallytriangular and other polygonal cross-sectional configurations.

The provision of spaced adjacent parallel ribs 14 in association withthe tubular portion 11 provides a structurally stable filament whichdoes not tend to bend, twist, or curl about the longitudinal axis of thetubular portion. Moreover, the spaced ribs and curved intervening wallsection provides a pair of spaced channels 18 which serve to retainwater on the brush filaments during use and to convey said water alongsaid channels 18 to the free ends of the filament for lubricating thepressure contact of the brush filaments against the surface beingwashed.

Filament 10 is made of a thermoplastic material, such as an alpha-olefinpolymer and copolymer. Generally speaking, filament 10 is obtained froma mixture of ethylene-propylene-polyisobutylene, ethylene vinyl acetate,and polyethylene. A specific example of a mixture for filament 10comprises by weight about 90% ethylenepropylene-polyisobutylene, aboutto 7% of ethylene vinyl acetate, and about 3% to 5% of a high densitylinear polyethylene. The ethylene-propylene-polyisobutylene ispreferably in the following proportions: ethylene 4%, propylene 87%, andpolyisobutylene 9%. The ethylene vinyl acetate is preferably in thefollowing proportions: ethylene 8% and vinyl acetate 92%. The ethylenevinyl acetate reduces the modulus of elasticity to provide a low tensilestrength and to limit elongation. Filament is provided with a breakingstrength in the order of 3 to 5 lbs. with elongation of not greater than10% when a 10 long sample is stretched at the rate of 1" per second.

A high density linear polyethylene in the amount of about 3% to 5% byweight provides a carrier for the addition of suitable coloringmaterials to the mixture so as to produce various colored filaments formaking a 4 brush attractive. Black, white, reds and greens and othercolors may be used, the color material being Well known and comprisingvarious oxides. The crystalline structure of the high density linearpolyethylene facilitates the introduction of color uniformly into thefilament material.

A mixture of the ingredients mentioned above are mechanically blended ina suitable well known mixing apparatus. After mixing they may be fed toa thermoplastic extruding device 20* of well known manufacture where themixture is heated into a homogeneous viscous mass. The material may beheated to about 435 F. for extrusion thereof.

Extruding device 20 includes an extruding head 21 having a die to formthe desired tubular and rib configuration illustrated in FIG. 1. Such adie includes an axially disposed mandrel (not shown) having an axialbore for admission of air under low pressure into the mass beingextruded through the die to form the hollow tube. Such air may beintroduced to the extruding head 21 by a conduit 22 connected to a highvolume low pressure air source (not shown), such air being furnished atabout .6 psi. at 8 c.f.m. The dimensions of the tubular filament aresubject to variation by the pressure air supplied to the extruding headand such a source of air may be furnished with a positive volumedisplacement adjusting means for controlling such dimensions of thetubular filament.

The extruded filament traverses an air gap 23 of approximately /2"between the exit face of the die and the introduction of the extrudedfilament into water bath 24.

Water bath 24 has a temperature of approximately F. to F. In the waterbath the extruded filament is drawn over a plurality of idle rolls ofapproximately Vs" diameter, made of suitable plastic material, such as plyvinyl chloride and arranged along an arcuate curve so as to producecontrolled stretching of the filament as it iS guided and pulled acrossthe idle rolls. In the example shown in FIG. 2 groups of idle rolls 25may be suitably arranged as exemplarily indicated so that the filamentmay pass through the water bath and exit therefrom at a temperature ofapproximately 140 F. to 160 F. A pair of pull rolls 27 draw the extrudedfilament through the bath 24 at a selected rate of speed.

Passing of the filament through the water bath and stretching thefilament therein serves to orient the material of the filament. Thedegree of stretching is carefully controlled by the rotation of pullrolls 27 and in the present invention the stretching of the filament isat a ratio of approximately 5.5 to 1. Full orientation of an extrudedfilament of the present composition would normally be drawn to anoriented ratio of about 8 /2 to 1- Thus, in the present filament therearrangement of the molecules with respect to the axis of the filamentis on y partially completed with respect to the normal parallel orientedrelation. Partial orientation is desired in H16 present example toreduce and eliminate splitting or lamination of the filament which mightproduce fraying of ends of the filament during use. Thus by onlypartially orienting the extruded filament a brush filament is providedwhich resists and eliminates entanglement With other filaments andpossible catching on projection or irregularities on a surface beingwashed.

After the extruded filament is drawn out of water bath 24 it may cut toa preselected length by suitable cutting means schematically indicatedat 29. The cut filament lengths may be collected into a group or abundle schematically indicated at 31 and may then be transported to ahot air oven schematically indicated at 33 where they may be subjectedto heat treatment for approximately two hours at an oven temperature ofbetween to 210 F. Such heat treatment of the partially oriented extrudedfilament serves to relieve stresses in the filaments. After heattreatment the filaments are withdrawn from the oven and are permitted toreturn to ambient tempera ture and may then be employed in themanufacture of a brush means.

The characteristics of filament 10 as provided by the formulationexemplified above and the process of extrusion, orienting, and heattreating forms a filament having a composition and structureparticularly desirable for filaments for vehicle washing brush means andother utility where a filament is required having the characteristicsdescribed below.

The filament 10 after being so processed provides a tensile breakingstrength of between 3 to 5 lbs. which occurs after not greaterelongation of the brush filament than approximately 10%. Thus when afilament engages a surface being washed and is exemplarily drawn into acrevice or in some way becomes caught on the surface, it will beapparent that the bristle will break before damage to the article orvehicle being washed.

Filaments 10 also provide straight filaments which do not twist or curlabout their longitudinal axis. Limitations on the tendency to curl arelimited to variations from a vertical line of not more than /2" when afilament 10 long is held vertically. The straightness of the filament iscaused by the particular arrangement of the molecular structure in thetubular portion and since full orientation or realignment of themolecules into parallel relation with the longitudinal axis has not beencompleted by reason of only partial orientation, any breaking of afilament results in a clean fracture without attendant stringiness,splitting or fraying in the filament portion adjacent to the fracture.

It should also be noted that the weight of the filament when dry isquite light, the weight of 1,000 filament inches (100 filaments 1 longeach) being in the range of approximately 10.8 gms. to 11.3 gms. Thefilament 10 is also provided with surface characteristics whichvirtually eliminate the deposit of a waxy type streak on the surfacebeing washed because of the composition described above which provides avirtually wax free base.

Filaments 10 have a density of about .9041 and a modulus of flexure ofabout between 1.0-1.2)(10 p.s.i. While the flexural modulus of the basecopolymer material may have been substantially higher, the presence ofthe ethylene vinyl acetate in the mixture reduces the flexural modulus.The relatively light weight characteristics of filament together withthe structural cross-sectional configuration provides a virtually selfsupporting brush filament when secured at one end and disposedhorizontally for a length of about 10'. Beyond 10" such as when brushfilaments of about 16" are employed the overall deflection of a filamentof about 16" long is only approximately 8" to 10 at its free end. Suchstructural rigidity of the brush filament together with their lightweight and relative stiffness permits the bristles to stand out from abrush core with relatively little drooping or sagging.

Since the filaments 10 may be used in car washes using hot water, thematerial of the present invention has been formulated to withstand andresist hot water (up to about 215 F.) without losing its partialorientation and remaining effectively operable.

Filament 10 has also exhibited heat resistance under conditions ofpressure referred to here as fiber stress as when a filament is rotatedat a selected peripheral tip speed with a selected interference (forexample 1") with a surface being washed in the presence of hot water.Deflection-temperature tests conducted under ASTM Test Method D648indicated fiber stress of 264 p.s.i. at 125-140 F. and of 66 p.s.i. atl85230 F. Filament 10 exhibited continuous resistance to heat withoutdeformation or deflection at temperatures of between 190-240 F.

Filament 10 is inert with respect to fungi and bacteria, has a waterabsorption characteristic of less than .0l%, and is chemically resistantto organic substances. When used against a surface with contact forcesbetween about 10 to 18 lbs., filament 10 exhibits good abrasionresistance.

Structural features are exemplified in FIG. 3 which schematically showsa brush means generally indicated at 40 formed from filaments 10. Brushmeans 40 may include a center core means 41 of well known constructionand upon which a plurality of parallel brush strips 42 may be mounted.Each brush strip 42 may include a plurality of filaments 10 held in saidbrush strip in usual manner and containing a desired density offilaments per unit of length of the brush strip. The core means 41 maybe carried upon shafts 43 supported in suitable bearings in arms 44which may be pivotally mounted for movement about a vertical axis 45 topermit the brush means 40 to swing into adjacent relation with a surfaceto be washed. One of the arms 44 may carry drive means (not shown) forrotating the core means 41 at selected speeds.

In such a brush means 40 provided with filaments 10 of the presentinvention when the brush means is rotated at relatively low speeds, suchas to r.p.m., the filaments 10 (about 22" long) stand straight out alongradial lines at such low speeds. Relatively low speeds in thisapplication means rotational speeds of between 50% to of rotationalspeeds of vehicle washing brush means utilizing prior proposed filamentsof substantial length such as 16" to 26". Those skilled in the artreadily recognize that a relatively low rotational speed for a vehiclewashing brush is advantageous when the filaments are standing out fullyas along a radial for providing a lower peripheral speed at the tip ofthe filaments, and thus a lower striking or impact pressure on thesurface being washed. Thus, tendency to streak or to grab antennas, doorhandles and the like is reduced.

In addition, a brush means 40 provided with filaments 10 operating at arelatively low rotational speed permits the filaments 10 to retain andhold water on the bristle. The particular cross-sectional configurationof filament 10 which provides essentially spaced channels along eachface thereof serves to hold water and to permit the water to flowstraight down the filament for deposit upon the surface being washed andfor lubrication of the passage of the bristle over the surface to removedirt and other foreign matter attached to the surface.

Another advantage of the provision of brush means 40 with filaments 10which permit relatively low rotational speeds together with therelatively stiff characteristics imparted to filament 10 because of thecross-sectional configuration is that the pumping action of thefilaments (occurring because of wind resistance of the filament duringrotation) is reduced and there is less distortion or defor mation of thebristle because of the wind resistance. Thus, the straight noncurlingfilament 10 provides an effective means for conveying and transferringwater to the surface being washed.

The structural configuration of filament 10 reduces the tendency of thefilament to kink under bending conditions. The composition of thematerial together with the structural configuration of the filamentaffords rapid recovery from bending conditions and even when thefilament is subjected to kinking the filament is capable of re coveringfrom such deformed kink condition to an effectively operable condition.

The filaments 10 when used in such a brush means 40 facilitate thediscrete separate independency of each filament with respect to anadjacent filament. It should be noted that the height of ribs 14 offilament 10 is so reduced with respect to the curved section of thetubular portion between said ribs that a rib of an adjacent filament isprevented from becoming deeply inserted between said ribs and inengagement therewith so that the two adjacent filaments would tend tointerlock or cling together. Thus, the cross-sectional configuration offilament 10 with the tubular portion virtually inscribed within apolygon defined by edges of the outwardly extending ribs provides afilament construction which is structurally stiff and rigid and '7 whichprevents clinging of adjacent filaments to each other. Such structuralstiffness of filament continues to be exhibited even when in the wethumid conditions prevalent in vehicle washing installations.

It will be understood by those skilled in the art that variousmodifications and changes may be made in the filament and compositiontherefor described above which come Within the spirit of this inventionand all such changes and modifications coming within the scope of theappended claims are embraced thereby.

I claim:

1. A brush filament of polymeric material comprising:

an elongated tubular portion having an external surface and having alongitudinal axis;

a plurality of longitudinal ribs in parallel relation to said axis andextending from said external surface of said tubular portion;

adjacent ribs having longitudinal rib edges defining a plane which isapproximately tangent to a portion of the external surface of thetubular portion lying between said adjacent ribs;

whereby an end of said filament engageable with a surface being brushedis adapted to contact said surface at said rib edges and tangentialsurface portion while providing a longitudinally extending channel forconveying fiuid to said surface during such contact.

2. A brush filament as stated in claim 1 wherein said filament has abreaking strength in the order of 3 to 6 lbs.

3. A brush filament as stated in claim 1 wherein said ribs are ofgenerally triangular cross-section and have rounded longitudinal ribedges.

4. A brush filament as stated in claim 1 wherein said polymeric materialis only partially oriented.

5. A brush filament as stated in claim 4 wherein said polymeric materialincludes by weight: ethylenepropylene-polyisobutylene in the order ofabout 90%, ethylene vinyl acetate in the order of from 5% to 7%, andhigh density polyethylene in the order of 3% to 5%.

6. In a brush construction for washing surfaces in the presence of afluid, such as Water and adapted to provide full brush configuration atrelatively low rotational speeds, comprising:

a core means; brush strip means on said core means; said brush stripmeans including light weight brush tubular filaments projecting fromsaid core means and having a cross-sectional configuration comprisingcurved wall sections having external surfaces,

spaced parallel ribs at ends of said curved wall sections and having ribedges lying in a plane approximately tangent to said external surface;

whereby said tubular filaments with said ribs maintain discrete separaterelation and provide therebetween fluid conducting channels forconveying fluid to free ends of said filaments for washing andlubricating a surface being cleaned without entanglement or interlockingof adjacent filaments.

7. A brush construction as stated in claim 6 wherein said brushfilaments comprise a partially oriented polymeric material, said partialorientation being insuflicient to produce a laminar arrangement withresultant splitting of said filaments.

8. A brush construction as stated in claim 7 wherein said brushfilaments have a breaking strength in the order of 3 to 6 lbs.

9. A brush construction as stated in claim 6 wherein said filaments arevirtually curl-free.

10. A light weight, low breaking strength, brush filament of polymericcomposition effectively operable in a hot humid environment underconditions of deflection, deformation and kinking of the filament,comprising in combination:

a hollow tubular member having a plurality of longi tudinal parallelexternal ribs;

said tubular member being formed of an extruded polymeric materialcomprising by weight: about ethylene-propylene-polyisobutylene, 5% to 7%of ethylene vinyl acetate, and 3% to 5% of high density polyethylene;

said member being partially oriented in the ratio of about between 5 and6 to 1.

11. A brush filament as stated in claim 10 wherein saidethylene-propylene-polyisobutylene is in the following proportions:ethylene about 4%, propylene about 87%, and polyisobutylene about 9%.

12. A brush filament as stated in claim 10 wherein the ethylene vinylacetate is in the proportions of about 8% ethylene and 92% vinylacetate.

13. A brush filament as stated in claim 10 wherein the fiber stress ofthe tubular member is in the range of about 264 p.s.i. at -140 F.

14. A brush filament as stated in claim 10 wherein the fiber stress ofthe tubular member is in the range of about 66 psi. at -230 F.

15. A brush filament as stated in claim 10 wherein the tubular memberhas a modulus of flexure of between about l.01.2 1O p.s.i.

16. A brush means comprising:

a core means;

and a plurality of brush filaments carried by said core means; saidbrush filaments comprising a tubular member having a plurality oflongitudinal parallel external ribs;

said tubular member comprising a polymeric material partially orientedin a ratio of about between 5 and 6 to 1; and

including a composition of ethylene-propylene-polyisobutylene, ethylenevinyl acetate, and polyethylene having a modulus of flexure of betweenl.01.2 10

psi.

References Cited UNITED STATES PATENTS 3,059,991 10/1962 Munt l5l59(A)3,238,553 3/1966 Bailey et al l5l59 3,344,457 10/1967 Grobert l5l593,256,545 6/1966 Lewis, Jr. et al l5l59 3.402,4l6 9/1968 Shaw et al.l5l59 3,411,979 11/1968 Lewis, Jr. l5159(A) FOREIGN PATENTS 531,55110/1956 Canada l5l59 1,303,179 7/1962 France 264-177(1 1,140,901 12/1962Germany 15159(A) 838,141 6/1960 Great Britain 15--159(A) PETER EELDMAN,Primary Examiner US. Cl. X.R.

